1. Field of the Invention
This invention relates to horticultural products and, more particularly, to an apparatus for sensing the liquid content in a growing medium for a horticultural product.
2. Background Art
Maintenance of a predetermined moisture content in a growing medium for a horticultural product is key to the healthy growth of the product. A myriad of different ways to maintain a minimum moisture content have been devised.
The most primitive system for maintaining moisture content is to add a predetermined amount of water or other liquid solution to the growing medium at regular time intervals. For example, it is common to water either weekly or biweekly.
However, this system does not take into account climate changes, be they change in temperature or humidity. As a consequence, the moisture content of the growing medium may vary significantly.
These problems have prompted the development of automatic watering systems. One type of system causes a constant drip of moisture into the growing medium. Variation in atmospheric conditions such as temperature and humidity may cause a significant variation in the moisture content over time with this type of system.
Other types of systems monitor the moisture content of the growing medium and automatically cause the delivery of water from a supply once the sensed moisture is below a predetermined level. These systems can become quite complicated and prone to failure. Conduits through which the water flows may restrict. Sensors may become clogged over time and operate ineffectively or altogether fail.
An alternative to systems that automatically sense and deliver moisture is the periodic manual sensing of moisture content. The most basic way of carrying this out is for the user to direct a finger against the growing medium to tactilely sense the degree of moisture. The problem with this is that the moisture cannot be sensed below finger depth. High heat may cause the surface moisture to evaporate while the growing medium maintains a substantial amount of moisture below the surface.
To more accurately sense the moisture content throughout the depth of the growing medium, it is known to use moisture sensing probes. The probes may be dimensioned to penetrate the full depth of the growing medium to give an accurate indication of moisture content even in the deepest portions of the growing medium.
The latter procedure requires that a sensing probe be kept in a convenient location to be accessible when needed. The possibility of losing the probe or not having it handy to observe a particular product is thus present. Probes of this type may represent a significant financial investment. Further, probes of this type may malfunction as after a buildup of foreign matter on, or corrosion of, the metal probe surface which contacts the growing medium.